Binding agent component for surface coating agents with improved adhesive properties

ABSTRACT

The invention relates to a binding agent composition, in particular an adhesive, containing at least one epoxy compound or at least one amino compound comprising at least two amino groups, or at least one hydroxy compound comprising at least two OH groups, or at least one mercapto compound comprising at least two mercapto groups, or at least one isocyanate comprising at least two NCO groups and a compound with chelating properties. The invention also relates to a method for producing binding agent compounds of this type and to the use of the same.

The present invention relates to a binder component, in particular anadhesive, comprising at least one epoxy compound or at least one aminocompound having at least two amino groups or at least one hydroxycompound having at least two OH groups or at least one mercapto compoundhaving at least two SH groups or at least one isocyanate having at leasttwo NCO groups, to a process for preparing such binder components, andto their use.

The adhesion of a surface coating composition to a substrate surface isof great importance for the durable functioning of the surface coatingcomposition. Exacting requirements in this respect are imposed inparticular on adhesives intended for joining two substrates to oneanother with maximum durability. The bond strength of such an adhesiveis on the one hand dependent on the compatibility between adhesive andthe substrate to which the adhesive is to be applied, i.e., on theadhesion between adhesive and substrate. In addition, however, the bondstrength also rests on the cohesion of the adhesive itself. Even smallchanges in the composition of the adhesive or in its molecular structuremay give rise to a drastic reduction in bond strength and hence eithermay make the adhesive completely unusable or may weaken, or even totallydestroy, a bond produced using such an adhesive.

It is therefore necessary right at the formulation stage of an adhesiveto ensure that individual components supplied to such an adhesive do notadversely affect its bond strength. Furthermore, as a result ofenvironmental influences and hence as a consequence of a change in themolecular structure of an adhesive, a bond produced using the adhesivemay suffer detraction from its bond strength over a certain period oftime to an extent such that it is no longer possible to ensure the firmbonding of two components.

The adhesion in particular of cured epoxy resins to metals, such as inthe structural bonding of metals using epoxy resin adhesives, forexample, falls considerably as a result of aging processes, particularlyunder the influence of moisture. In many cases this necessitates the useof costly and inconvenient pretreatment methods, priming being oneexample. Such pretreatment, however, is a disadvantage from thestandpoint of cost. In many cases, moreover, such as with accidentrepairs in the bodywork area, these pretreatment methods can only beused to a limited extent. This is particularly true of the steel oraluminum components frequently employed in bodywork construction, sincethe adhesion of two-part epoxy resin adhesives to steel or aluminum,particularly when substrate pretreatment is inadequate, is frequentlyvery poor.

As a consequence of these aging processes the adhesive may loseflexibility, cohesion or adhesion, or one or more other importantproperties. Especially when an adhesive is to be used outdoors it isnecessary to ensure that such changes, brought about for example bymoisture, which lead to a loss in bond strength do not occur at all, oroccur only to an unavoidably small extent.

This need has led to a variety of possibilities being proposed to giveadhesive bonds improved long-term stability even under the influence ofenvironmental conditions such as moisture.

Thus, for example, the prior art discloses hot-curing epoxy resinadhesives whose adhesion to aluminum surfaces under normal conditions isadequate. A disadvantageous consequence affecting these adhesives,however, is that for certain applications, in extreme cases, the agingstability is not adequate.

It was therefore an object of the present invention to provide surfacecoating compositions which exhibit effective substrate adhesion evenunder extreme ambient conditions, particularly in cases of substantialmoisture. The present invention was based in particular on an object ofproviding adhesives which exhibit excellent substrate adhesion and alsoexcellent cohesion to a multiplicity of substrates, but particularly tometals, even under moist conditions.

It has now been found that surface coating compositions which comprisecompounds with chelating ligands improve the adhesion of such surfacecoating compositions to metallic substrates in particular. The objectson which the invention is based are therefore achieved by bindercomponents as described within the scope of the text below and as may beused as constituents of surface coating compositions, especially ofadhesives.

The present invention accordingly provides a binder component comprisingat least one epoxy compound or at least one amino compound having atleast two amino groups or at least one hydroxy compound having at leasttwo OH groups or a mercapto compound having at least two SH groups or atleast one isocyanate having at least two NCO groups and at least onecompound having chelating properties.

By a binder component in the context of the present invention is meant,therefore, a mixture comprising at least one epoxy compound or at leastone amino compound having at least two amino groups or at least onehydroxy compound having at least two OH groups or at least one mercaptocompound having at least SH groups or at least one isocyanate having atleast two NCO groups and at least one compound having chelatingproperties. A binder component of the invention must therefore includeat least one compound having chelating properties.

The term “include” here in the context of the present invention embracesnot only those compounds having chelating properties that are presentper se in the form employed in the binder component but also compoundshaving chelating properties that have been incorporated into the binderby a chemical reaction and are bonded covalently, for example, to saidbinder.

A binder composition for the purposes of the present invention means acomposition which is suitable for the preparation of a binder. The term“binder composition” as used in the context of the present text relatespot only to binder compositions in the form of a one-component systembut also to binder compositions which are present in two-component ormulticomponent systems and which have to be mixed by the user in orderto prepare the binder. In the context of the present invention,accordingly, the term “binder composition” is used for the physicalentirety of the binder components needed for preparing a binder,irrespective of whether these components are already present in themixed state or are still spatially separate. Decisive for the use of theterm “binder composition” is the question of whether the individualbinder components have been combined or blended in a form suitable forpreparation of a binder.

A binder component of the invention may therefore be part of aone-component or multicomponent binder composition, the term “bindercomposition” referring to the entirety of all the constituents needed toform a binder. In the case of binders which form by chemical curing,such as are described in the context of the present invention, theindividual constituents are often referred to as “resin” and “hardener”,with resin and hardener reacting to form a binder under certain externalconditions, including for example customary ambient conditions, to formcovalent chemical bonds and to form polymers.

The term “binder component” as used in the context of the present textrefers here both to the “resin” component and to the “hardener”component, unless expressly stated otherwise in each case.

For example, a binder composition of the invention may in accordancewith the present invention include only one binder component of theinvention and a further binder component which is not designed inaccordance with the invention. Thus, for example, a binder compositionof the invention may include as binder component a resin which comprisesan aromatic amino compound having chelating properties. Such a resinconstitutes a binder component of the invention. As hardener, however,the binder composition may include, for example, an amino compound whichdoes not comprise an aromatic amino compound having chelating propertiesand which thus is not a binder component of the invention. On the basisof the binder component of the invention that is present in the bindercomposition, however, the overall binder composition does have theadvantages of the invention. Conversely it is also possible for a bindercomposition of the invention to include, for example, a noninventiveresin and an inventive hardener as binder components. The invention,however, also embraces those cases where a binder composition of theinvention comprises two or more binder components of the invention.

The term “surface coating composition” as used in the context of thepresent text relates to a composition comprising at least one bindercomponent of the invention. A surface coating composition in accordancewith the present invention may contain exclusively one bindercomposition of the invention. It is, however, likewise possible, andcontemplated, for a surface coating composition of the invention toinclude further additives as well as a binder composition in accordancewith the present invention.

In one first embodiment of the present invention a binder component ofthe invention, as can be used, for example, as a resin, comprises atleast one epoxy compound. Suitable epoxy compounds include in principleall types of compound which contain an oxirane ring.

Examples of suitable epoxy compounds are epoxidized soybean oil,epoxidized olive oil, epoxidized linseed oil, epoxidized castor oil,epoxidized groundnut oil, epoxidized corn oil, epoxidized cottonseedoil, and glycidyl compounds.

Glycidyl compounds contain a glycidyl group attached directly to acarbon, oxygen or nitrogen atom. Glycidyl or methylglycidyl esters areobtainable by reacting a compound having at least one NH, OH or carboxylgroup in the molecule and epichlorohydrin and/or glycerol dichlorohydrinand/or methyl-epichlorohydrin. The reaction takes place advantageouslyin the presence of bases.

As compounds having at least one carboxyl group in the molecule it ispossible, for example, to use aliphatic carboxylic acids. Examples ofthese carboxylic acids are glutaric acid, adipic acid, pimelic acid,suberic acid, azelaic acid, sebacic acid or dimerized or trimerizedlinoleic acid, acrylic acid, methacrylic acid, caproic acid, caprylicacid, lauric acid, myristic acid, palmitic acid, stearic acid orpelargonic acid, and the monocarboxylic or polycarboxylic acidsmentioned in the further course of this text. Examples of suitabledicarboxylic acids are propanedicarboxylic acid, butanedicarboxylic acid(succinic acid), pentanedicarboxylic acid (glutaric acid),hexanedicarboxylic acid (adipic acid), heptanedicarboxylic acid,octanedicarboxylic acid, nonanedicarboxylic acid or decanedicarboxylicacid, dimmer fatty acid or trimer fatty acid, or a mixture of two ormore thereof. Likewise suitable are the unsaturated dicarboxylic acids,maleic acid, fumaric acid, malic acid, pentenedicarboxylic acid,hexenedicarboxylic, heptenedicarboxylic acid or octenedicarboxylic acid.

Likewise suitable are cycloaliphatic carboxylic acids such ascyclohexanecarboxylic acid, tetrahydrophthalic acid,4-methyltetrahydrophthalic acid, hexahydrophthalic acid,endomethylenetetrahydrophthalic acid or 4-methylhexahydrophthalic acid.Additionally suitable are aromatic monocarboxylic and polycarboxylicacids such as benzoic acid, phthalic acid, isophthalic acid, trimelliticacid or pyromellitic acid.

Glycidyl ethers or methylglycidyl ethers can also be obtained byreacting a compound having at least one free alcoholic OH group or aphenolic OH group and a suitably substituted epichlorohydrin underalkaline conditions or in the presence of an acidic catalyst withsubsequent alkali treatment. Ethers of this type derive, for example,from acyclic alcohols such as ethylene glycol, diethylene glycol orhigher poly(oxyethylene)glycols, propane-1,2-diol orpoly(oxypropylene)glycols, butane-1,4-diol,poly(oxytetramethylene)glycols, pentane-1,5-diol, hexane-1,6-diol,hexane-2,4,6-triol, glycerol, 1,1,1-trimethylolpropane,bistrimethylolpropane, pentaerythritol, and sorbitol, and also frompolyepichlorohydrins, butanol, amyl alcohol, and pentanol, and frommonofunctional alcohols such as isooctanol, 2-ethylhexanol, isodecanolor technical-grade alcohol mixtures, examples being technical-gradefatty alcohol mixtures.

Further suitable ethers derive also from cycloaliphatic alcohols such as1,3- or 1,4-dihydroxycyclohexane, 1,3- or 1,4-cyclohexanedimethanol,bis(4-hydroxycyclohexyl)-methane, 2,2-bis(4-hydroxycyclohexyl)propane or1,1-bis(hydroxymethyl)cyclohex-3-ene or they possess aromatic nucleisuch as N,N-bis(2-hydroxyethyl)aniline. Suitable epoxy compounds mayalso derive from mononuclear phenols, such as from phenol, resorcinol orhydroquinone, for example, or are based on polynuclear phenols such asbis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane(bisphenolA), 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane or4,4′-dihydroxydiphenyl sulfones or on condensation products of phenolwith formaldehyde that are obtained under acidic conditions,phenol-novolaks for example.

Examples of further epoxides suitable in the context of the presentinvention are glycidyl 1-naphthyl ether, glycidyl 2-phenylphenyl ether,biphenyl-2-yl glycidyl ether, N-(2,3-epoxypropyl)phthalimide or2,3-epoxypropyl 4-methoxyphenyl ether.

Suitability in the context of the present invention is additionallypossessed by cycloaliphatic epoxy resins such as3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate orbis((3,4-epoxycyclohexyl)methyl)adipate.

Likewise suitable are N-glycidyl compounds, such as are obtainable bydehydrochlorinating the reaction products of epichlorohydrin with amineswhich contain at least one amino hydrogen atom. Examples of such aminesare aniline, N-methylaniline, toluidine, n-butylamine,bis(4-aminophenyl)methane, m-xylylenediamine orbis(4-methylaminophenyl)methane.

Epoxy compounds suitable in the context of the present invention containat least one epoxy group, but preferably more than one epoxy group.Suitable, for example, are epoxy compounds containing at least about1.1, 1.3 or 1.5 epoxy groups per molecule, but in particular two or moreepoxy groups. If the number of epoxy groups in an epoxy compound whichcan be used in accordance with the invention does not give a wholenumber, then the compound is a mixture of epoxy compounds having adifferent number of epoxy groups. In this case the average value for allthe compounds present which carry epoxy groups is stated as the numberof epoxy groups per molecule.

In the epoxy compounds which can be used in the context of the presentinvention the epoxy group can be arranged either terminally or centrallywithin the molecule. If an epoxy compound which can be used inaccordance with the invention carries more than one epoxy group, thenthese epoxy groups can be situated at any positions within the molecule.If, in the context of the present invention, for example, polymericepoxides which carry more than, for example, two or three epoxy groupsare used, then the epoxy groups may be arranged, for example, at theends of the polymer backbone, within the polymer backbone or on sidechains.

In one preferred embodiment epoxy compounds used include bisphenol Adiglycidyl ethers, epoxidized diolefins such as 1,2,5,6-diepoxyhexane,1,2,4,5-diepoxycyclohexane, dicyclopentadiene diepoxide, dipentenediepoxide, vinylcyclohexene diepoxide, epoxidized polyolefinicallyunsaturated carboxylic acids such as methyl 9,10,12,13-diepoxystearateor the dialkyl ester of 6,7,10,11-diepoxyhexadecane-1,16-dicarboxylicacid.

Likewise suitable are epoxidized mono-, di- or polyesters, epoxidizedmono-, di- or polyurethanes, epoxidized mono-, di- or polycarbonates orepoxidized mono-, di- or polyacetals, especially those having at leastone cycloaliphatic ring which carries at least two epoxy groups.Suitable polyesters, polyurethanes or polycarbonates are, for example,the polyesters, polyurethanes or polycarbonates stated within the textbelow, which may be provided in a manner known to the skilled workerwith one or more epoxy groups. Another widespread class of polyepoxidesare, for example, epoxy polyethers, such as are obtainable by reacting ahalogenated epoxide, epichlorohydrin or epibromohydrin,3-chloro-1,2-epoxyoctane and the like, for example, with a polyol.

Compounds additionally suitable as a constituent of a binder componentof the invention are, for example, amino compounds having at least twoamino groups.

Suitable nonaromatic amino compounds having at least two amino groupsinclude in principle all diamines and polyamines.

Examples of suitable such compounds are ethylenediamine,propylenediamine, butylenediamine, hexamethylenediamine,2,4,4-trimethylhexamethylene-diamine, diethylenetriamine,1,12-diaminododecane, diamines derived from dimer fatty acids ortriamines derived from trimer fatty acids, or a mixture of two or moreof said compounds.

Examples of suitable cycloalkyl compounds which carry amino groups arecyclohexylenediamine, dicyclohexylenediamine,4,4′-dicyclohexylmethanediamine, isophoronediamine,1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, andhydrogenated toluenediamines such as 1-methyl-2,4-diaminocyclohexane,1-methyl-2,6-diaminocyclohexane, and the like.

Likewise suitable as amino compounds are, for example,1,4-diaminobenzene, diaminotoluene, m- or p-phenylenediamine,diaminobiphenyl, o-, m- or p-toluidine, 2,4-xylidine, 2,4- and2,6-toluenediamine and corresponding mixtures, 4,4′-diphenylenediamine,naphthyldiamines, bis(4-aminophenyl)methane or mixtures of two or moreof said compounds.

Likewise suitable as amino compounds are, for example,1,3,5-trisaminoalkyl, cycloalkyl, and aryl isocyanurates. Examples thatmay be mentioned include the following:1,3,5-tris(6-aminohexyl)isocyanurate,1,3,5-tris(6-aminopropyl)isocyanurate,1,3,5-tris(6-aminoethyl)isocyanurate,1,3,5-tris(3-aminophenyl)isocyanurate, and1,3,5-tris(4-methyl-3-aminophenyl)isocyanurate. It is likewise possibleto employ mixtures of two or more of said compounds.

Likewise suitable as amino compounds for the purposes of the presentinvention are polyesters having an amino group as end groups or sidegroups or both. Polyesters of this kind can be obtained, for example, bypolymer-analogous reaction of a carboxyl-carrying polyester withpolyamines, the polyester containing either amino end groups or aminoside groups or both.

Likewise suitable as amino compounds for the purposes of the presentinvention are polyetheramines. Polyetheramines are prepared, forexample, by polymer-analogous reaction from polyetherpolyols. Suitablepolyetherpolyols are obtained normally by reacting a starter compoundcontaining at least two reactive hydrogen atoms with alkylene or aryleneoxides, examples being ethylene oxide, propylene oxide, butylene oxide,styrene oxide, tetrahydrofuran and epichlorohydrin, or mixtures of twoor more thereof.

Examples of suitable starter compounds include water, ethylene glycol,propylene 1,2- or 1,3-glycol, butylene 1,4- or 1,3-glycol,hexane-1,6-diol, octane-1,8-diol, neopentyl glycol,1,4-hydroxymethylcyclohexane, 2-methyl-1,3-propanediol, glycerol,trimethylolpropane, hexane-1,2,6-triol, butane-1,2,4-triol,trimethylolethane, pentaerythritol, mannitol, sorbitol,methylglycosides, sugars, phenol, isononylphenol, resorcinol,hydroquinone, 1,2,2- or 1,1,2-tris(hydroxyphenyl)ethane, ammonia,methylamine, ethylenediamine, tetra- or hexamethyleneamine,triethanolamine, aniline, phenylenediamine, 2,4- and 2,6-diaminotoluene,and polyphenylpolymethylene-polyamines, as obtainable byaniline-formaldehyde condensation.

The functionalization of the polyetherpolyols with amino groups takesplace in a manner known to the skilled worker. Thus, for example,conventional polyetherpolyols can be converted into the correspondingpolyetheramines by reacting the terminal OH groups with ammonia orprimary amines in accordance with methods known from the literature.

Such amino-functionalized polyetherpolyols are obtainable commercially,for example, under the trade name JEFFAMIN® in different compositions.Examples that may be mentioned are the Jeffamin grades D 230, D 400, andD 2000, based on difunctional polypropylene glycols, the grades T 403, T3000, and T 5000, based on trifunctional polypropylene glycols, thegrades ED 600, ED 900, ED 2001, and ED 6000, based on difunctionalpolyethylene glycols, and the grades M 300, M 600, M 1000, and M 2070,based on monofunctional polypropylene glycols.

Likewise suitable as amino compounds for the purposes of the presentinvention are amino-carrying polyacetals. Polyacetals are compounds suchas are obtainable by reacting glycols, diethylene glycol or hexanediolfor example, with formaldehyde. Polyacetals which carry n amino groupsand can be used in the context of the invention can also be obtained bypolymerizing cyclic acetals. The functionalization of such polyacetalswith amino groups is subject to the same comments as already made in thecontext of the description of the polyesters.

Likewise suitable as amino compounds for the purposes of the presentinvention are amino-carrying polycarbonates. Polycarbonates can beobtained, for example, by reacting the abovementioned polyols,particularly diols such as propylene glycol, butane-1,4-diol orhexane-1,6-diol, diethylene glycol, triethylene glycol or tetraethyleneglycol, or mixtures of two or more thereof, with diaryl carbonates,diphenyl carbonate for example, or phosgene. The functionalization ofthe polycarbonates with amino groups is subject to the same comments asalready made in the context of the description of the polyesters.

Likewise suitable as amino compounds for the purposes of the presentinvention are amino-carrying polylactones. Suitable polylactones arepreferably those deriving from compounds of the general formulaHO—(CH₂)_(z)—COOH where z is a number from 1 to about 20. Examples areε-caprolactone, β-propiolactone, γ-butyrolactone ormethyl-ε-caprolactone, or mixtures of two or more thereof. Thefunctionalization of the polylactones with amino groups is subject tothe same comments as already made in the context of the description ofthe polyesters.

Likewise suitable as amino compounds for the purposes of the presentinvention are polyethylenimines. Suitable polyethylenimines may beobtained by polymerizing reaction of ethylenimine, and have a molecularweight of from about 300 to about 100 000.

Likewise suitable as amino compounds for the purposes of the presentinvention are amino-carrying polyamides. Suitable polyamides may beprepared, for example, by reacting the abovementioned dicarboxylic acidswith corresponding diamines. Examples of suitable diamines are thosewhich have a molecular weight of from about 32 to about 200 g/mol andcontain at least two primary, two secondary or one primary and onesecondary amino group(s). Examples thereof are diaminoethane,diaminopropanes, diaminobutanes, diaminohexanes, piperazine,2,5-dimethylpiperazine,amino-3-aminomethyl-3,5,5-trimethylcyclohexane(isophorone-diamine,IPDA), 4,4′-diaminodicyclohexylmethane, 1,4-diaminocyclohexane,aminoethylethanolamine, hydrazine, hydrazine hydrate or, in smallamounts if desired, diamines such as the diethylenetriamine or1,8-diamino-4-aminomethyloctane. Another possibility is the synthesisfrom lactams such as ε-caprolactam or aminocarboxylic acids such as11-aminoundecanoic acid. The functionalization of the polyamides withamino groups is subject to the same comments as already made in thecontext of the description of the polyesters.

Compounds additionally suitable as a constituent of a binder componentof the invention are, for example, mercapto compounds or hydroxycompounds having at least two SH or OH groups. A description is givenbelow of polyol compounds and their preparation, such as they may beused, for example, in the context of the present invention. In principleit is the case that for the purposes of the present invention it is alsopossible to employ the corresponding mercapto compounds such as aredescribed by imaginary substitution of the OH groups in the polyolsdescribed below with SH groups.

Of such compounds, suitability is possessed, for example, by the lowmolecular mass polyhydroxy and polymercapto compounds, such as ethyleneglycol, propylene 1,2- or 1,3-glycol, butylene 1,4- or 1,3-glycol,hexane-1,6-diol, octane-1,8-diol, neopentyl glycol,1,4-hydroxymethylcyclohexane, 2-methyl-1,3-propanediol, glycerol,trimethylolpropane, hexane-1,2,6-triol, butane-1,2,4-triol,trimethylolethane, pentaerythritol, mannitol, sorbitol,methylglycosides, sugars, phenol, isononylphenol, resorcinol,hydroquinone, 1,2,2- or 1,1,2-tris(hydroxyphenyl)-ethane, ethylenedimercaptan, propylene-1,2-dithiol or -1,3-dithiol, butylene-1,4-dithiolor -1,3-dithiol, hexane-1,6-dithiol, octane-1,8-dithiol,neopentyldithiol, 1,4-mercaptomethylcyclohexane,2-methyl-1,3-propanedithiol, thioglycerol, trimercaptopropane,hexane-1,2,6-trithiol, butane-1,2,4-trithiol, trimercaptoethane,thiopentaerythritol, mercaptomannitol, mercaptosorbitol, thio sugars,thiophenol, isononylthiophenol, thioresorcinol, thiohydroquinone, and1,2,2- or 1,1,2-tris(thiophenyl)ethane.

Likewise suitable are polymeric mercapto and hydroxy compounds (polymerpolymercaptans and polymer polyols) having a molecular weight of, forexample, more than about 200 or more than about 500. These are, inparticular, polyurethanepolymercaptans and polyurethanepolyols,polyesterpolymercaptans and polyesterpolyols, polyetherpolymercaptansand polyetherpolyols, and further polymercaptan and polyol compoundssuch as are described within the text below.

Suitable polyurethanepolymercaptans and polyurethanepolyols arepreparable, for example, using the following building blocks:

-   -   a) at least one polyisocyanate,    -   b) at least one polymercaptan or polyol or a mixture of two or        more thereof.

If desired it is possible in addition to use up to about 20% by weightof low molecular mass compounds (building block c) suitable forintroducing SH or OH end groups, based on the polyurethane weight.

Suitable isocyanates (building block a) are any desired organiccompounds containing on average more than one, in particular 2,isocyanate group(s).

It is preferred to use diisocyanates Q(NCO)₂ in which Q is an aliphatic,optionally substituted hydrocarbon radical having 4 to about 12 carbonatoms, an optionally substituted cycloaliphatic hydrocarbon radicalhaving 6 to about 15 carbon atoms, an optionally substituted aromatichydrocarbon radical having 6 to about 15 carbon atoms or an optionallysubstituted araliphatic hydrocarbon radical having 7 to about 15 carbonatoms. Examples of such diisocyanates are tetramethylene dilsocyanate,hexamethylenediisocyanate (HDI), dodecamethylene diisocyanate, dimerfatty acid diisocyanate, 1,4-diisocyanatocyclohexane,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane(isophoronediisocyanate, IPDI), 4,4′-diisocyanatodicyclohexylmethyl,2,2-bis(4-isocyanatocyclohexyl)propane, 1,3- and1,4-diisocyanatobenzene, 2,4- or 2,6-diisocyanatotoluene (2,4- or2,6-TDI) or a mixture thereof, 2,2′-, 2,4 or,4,4′-diisocyanatodiphenylmethane (MDI), tetramethylxylylene diisocyanate(TMXDI), p-xylylene diisocyanate, and mixtures of these compounds.

Preference is given to aliphatic diisocyanates, particularly m- andp-tetramethylxylylene diisocyanate (TMXDI) and isophorone diisocyanate(IPDI).

It is of course also possible to use as well, proportionally, the higherpolyfunctional polyisocyanates known per se in polyurethane chemistry orelse modified polyisocyanates known per se, examples beingpolyisocyanates containing carbodiimide groups, allophanate groups,isocyanurate groups, urethane groups or biuret groups.

Suitable building blocks (b) are SH— or OH-terminated polymercaptans orpolyols or those which carry pendant SH or OH groups (polymer mercaptansor polymer polyols) or polymercaptan mixtures or polyol mixtures, suchas are known to the skilled worker for polyurethane preparation and canbe used customarily in the preparation of polyurethanes. In the contextof the present invention it is possible to use polymer mercaptans orpolymer polyols from the group consisting of polyetherpolymercaptans andpolyetherpolyols, polyesterpolymercaptans and polyesterpolyols,polyetheresterpolymercaptans and polyetheresterpolyols,polyalkylenedimercaptans or polyalkylenepolyols, polythiocarbonates andpolythioacetals, or a mixture of two or more thereof, having in eachcase 2, 3, 4 or more SH or OH groups.

The polymer polymercaptans or polymer polyols described are suitable perse also as individual constituents of a binder component of theinvention. The following description of the polymer polymercaptans orpolymer polyols should therefore be understood such that the statedpolymer polymercaptans or polymer polyols are also suitable as aconstituent of a binder component in the sense of the invention.

The stated polymer polymercaptans or polymer polyols and theirpreparation are known from the state of the art or can be provided bythe skilled worker with the aid of his or her general art knowledge.Thus, for example, polyesterpolymercaptans or polyesterpolyols can beprepared by reacting dicarboxylic acids with dithiols or diols or higherpolythiols or polyols, or with a mixture of dithiols or diols and higherpolythiols or polyols, or with an excess of dithiols or diols or higherpolythiols or polyols, or mixtures thereof, and also by ring-openingepoxidized esters, such as epoxidized fatty acid esters, for example,with thiols or alcohols.

Suitable polyesterpolythiols or polyesterpolyols are obtainable, forexample, by reacting dicarboxylic acids with dithiols or diols or higherpolythiols or polyols, or with a mixture of dithiols or diols and higherpolythiols or polyols, or with an excess of dithiols or diols or higherpolythiols or polyols, or mixtures thereof, and also by ring-openingepoxidized esters, such as epoxidized fatty acid esters, for example,with thiols or alcohols. Polycaprolactonedithiols orpolycaprolactonediols as well, preparable for example fromε-caprolactone and dithiols or diols or higher polythiols or polyols,are suitable as polyesterpolythiols or polyesterpolyols. In the contextof the present invention it is possible to use, for example,polyesterpolythiols which are obtainable from low molecular massdicarboxylic acids such as succinic acid, glutaric acid, adipic acid,isophthalic acid, terephthalic acid or phthalic acid, or from a mixtureof two or more thereof, with an excess of linear or branched, saturatedor unsaturated aliphatic dithiols having about 2 to about 12 carbonatoms. If desired, in the preparation of the polyesterpolythiols it isalso possible for there to be a small fraction of thiols with a higherfunctionality, examples of which include thioglycerol,trimethylthiolpropane, triethylthiolpropane, thiopentaerythritol or thiosugars, such as thiosorbitol, thiomannitol or thioglucose.

Polyesterpolythiols or polyesterpolyols suitable in the context of thepresent invention for preparing polyurethanepolythiols orpolyurethanepolyols are essentially linear and have, for example, amolecular weight of from about 1 000 to about 50 000 and also an SH orOH number of from about 10 to about 200, such as about 20 to 80, forexample.

Polycaprolactonedithiols or polycaprolactonediols as well, preparablefor example from ε-caprolactone and dithiols or diols or higherpolythiols or polyols, are also suitable as polyesterpolythiols orpolyesterpolyols. In the context of the present invention, for thepreparation of the polyurethanepolythiols or polyurethanepolyols, it ispossible to use, for example, polyesterpolythiols or polyesterpolyolswhich are obtainable from low molecular mass dicarboxylic acids such assuccinic acid, glutaric acid, adipic acid, isophthalic acid,terephthalic acid or phthalic acid, or from a mixture of two or morethereof, with an excess of linear or branched, saturated or unsaturatedaliphatic dithiols or diols having about 2 to about 12 carbon atoms. Ifdesired, in the preparation of the polyesterpolythiols orpolyesterpolyols, it is also possible for there to be a small fractionof higher-functionality mercaptans or alcohols, examples of whichinclude glycerol, trimethylolpropane, triethylolpropane, pentaerythritolor sugar alcohols, such as sorbitol, mannitol or glucose, and also thecorresponding thio analogs of said hydroxy compounds. Thepolyesterpolythiols or polyesterpolyols, however, are preferablyessentially linear.

Polythioacetals or polyacetals that may be mentioned include for examplethe polycondensation products of formaldehyde and dithiols or diols orpolythiols or polyols, or mixtures thereof, in the presence of acidiccatalysts.

Polyetherpolyols or can be obtained, for example, by homopolymerization,copolymerization or block polymerization of alkylene oxides such asethylene oxide, propylene oxide or butylene oxide, or mixtures of two ormore thereof, or by reacting polyalkylene glycols with difunctional ortrifunctional alcohols.

Likewise suitable are the polymerized ring-opening products of cyclicthioethers or ethers, tetrahydrofuran for example, with correspondingthiols or alcohols as starter molecules. If ester compounds are used asstarter molecules, oligoesters or polyesters for example, thenpolyetheresters are obtained, containing both ether and ester groups.Said compounds can likewise be used as a polythiol component or polyolcomponent in the preparation of polyurethanepolythiols orpolyurethanepolyols.

In one preferred embodiment of the present invention thepolyetherpolyols or compounds that are thio analogs thereof used in thepreparation of polyurethanepolyols are the alkoxylation products,particularly the ethoxylation or propoxylation products, of difunctionalor trifunctional thiols and/or alcohols. Difunctional or trifunctionalalcohols used are in particular alcohols selected from the groupconsisting of ethylene glycol, diethylene glycol, triethylene glycol,1,2-propanediol, dipropylene glycol, the isomeric butanediols,hexanediols, octanediols, technical-grade mixtures of hydroxy fattyalcohols having 14 to 22 carbon atoms, especially hydroxystearylalcohol, trimethylolpropane or glycerol or mixtures of two or more ofthe stated alcohols and/or of the compounds that are thio analogs.

Besides the abovementioned polythiols or polyols it is possible as wellto use, proportionally, as building block b) linear or branched,saturated or unsaturated aliphatic, monofunctional alcohols, especiallymethanol, ethanol, the isomers of propanol, of butanol or of hexanol,and fatty alcohols having about 8 to about 22 carbon atoms, examplesbeing octanol, decanol, dodecanol, tetradecanol, hexadecanol oroctadecanol, and the compounds that are thio analogs thereof. The statedfatty thiols or fatty alcohols are obtainable, for example, by reductionof natural fatty acids and can be used either as single substances or inthe form of their technical-grade mixtures. Highly suitable, forexample, are linear monothiols or monoalcohols, and particularly thosehaving about 4 to about 18 carbon atoms. Instead of the linear orbranched aliphatic thiols or alcohols or in a blend with them it is alsopossible to use monoalkyl polyether alcohols of varying molecularweight, preferably in the molecular weight ranges from about 1 000 toabout 2 000, and/or the compounds that are thio analogs thereof thereof.

Likewise suitable for use as building block b) are polyfunctional, inparticular difunctional, thiols or alcohols, such as are obtainable, forexample, by hydrogenating dimeric or oligomeric fatty acids or theiresters, castor oil, with C₁₋₄ alkyl alcohols, ring-opened, epoxidizedfats or oils, C₁₂₋₁₈ fatty acid diethanolamides, monoglycerides ofaliphatic C₈₋₂₂ fatty acids, polypropylene glycols or polysiloxanescontaining terminal OH groups, or mixtures of two or more of saidcompounds can be employed.

In order to introduce SH or OH end groups such as may be employed in thecontext of the present invention for preparing thepolyurethanepolythiols of polyurethanepolyols as building block c)suitable examples include polyvalent, in particular divalent, alcoholssuch as ethylene glycol, propylene glycol, propane-1,3-diol,butane-1,4-diol or hexane-1,6-diol, and/or the compounds that are thioanalogs. Low molecular mass polyesterdithiols or polyesterdiols as well,such as succinic, glutaric or adipic bis(hydroxyethyl)esters orbis(mercaptoethyl)esters, or a mixture of two or more thereof, or lowmolecular mass dithiols or diols containing ether groups, such asdiethylene glycol, triethylene glycol, tetraethylene glycol, dipropyleneglycol, tripropylene glycol or tetrapropylene glycol, and the compoundsthat are thio analogs, can also be used as building block c).

Likewise suitable as polymer polyols or polymer polythiols arepolyacrylates which carry SH or OH groups. These polyacrylates areobtainable, for example, by polymerizing ethylenically unsaturatedmonomers which carry an SH or OH group. Monomers of this kind areobtainable, for example, by esterifying ethylenically unsaturatedcarboxylic acids and difunctional thiols or alcohols, the thiol oralcohol generally being in a slight excess. Examples of ethylenicallyunsaturated carboxylic acids suitable for this purpose include acrylicacid, methacrylic acid, crotonic acid or maleic acid. Correspondingesters which carry SH groups are, for example, 2-mercaptoethyl acrylate,2-mercaptoethyl methacrylate, 2-mercaptopropyl acrylate,2-mercaptopropyl acrylate, 2-mercaptopropyl methacrylate,3-mercaptopropyl acrylate or 3-mercaptopropyl methacrylate, or mixturesof two or more thereof; corresponding esters which carry OH groups are,for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,2-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropylmethacrylate, 3-hydroxypropyl acrylate or 3-hydroxypropyl methacrylate,or mixtures of two or more thereof.

As isocyanate which is present in the binder component of the inventionand has at least two NCO groups suitability is possessed by, preferably,aromatic isocyanates, e.g., diphenylmethane diisocyanate, either in theform of the single isomers, as an isomer mixture of the 2,4′/4,4′isomers, or else carbodiimide-liquefied diphenylmethane diisocyanate(MDI), which is known, for example, under the trade name Isonate 143 L.It is additionally possible to use what is called “crude MDI”, in otherwords the isomer/oligomer mixture of MDI, such as are obtainable, forexample, under the trade name PAPI or Desmodur VK commercially. It isalso possible to use what are called quasi-prepolymers, i.e., reactionproducts of MDI and/or of tolylene diisocyanate (TDI) with low molecularmass diols such as ethylene glycol, diethylene glycol, propylene glycol,dipropylene glycol or triethylene glycol, for example. Although theaforementioned isocyanates are the particularly preferred isocyanates itis also possible in special cases to use aliphatic and/or cycloaliphaticdiisocyanates or polyisocyanates, such as hydrogenated MDI (H₁₂MDI),tetramethylxylylene diisocyanate (TMXDI),1-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane (IPDI),hexane 1,6-diisocyanate (HDI), biuretization product of HDI,isocyanuratization product of HDI or dimer fatty acid diisocyanate.Suitable isocyanates having at least two NCO groups also includepolyurethane prepolymers containing free isocyanate groups, which areadducts of an excess of polyfunctional isocyanates with polyfunctionalalcohols: for instance, the reaction products of an aromatic oraliphatic diisocyanate with ethylene glycol, propylene glycol, glycerol,trimethylolpropane or pentaerythritol. Reaction products ofdiisocyanates with polyetherpolyols, e.g., polyetherpolyols based onpolyethylene oxide or on polypropylene oxide, as well, can be used asprepolymers. A large number of such polyetherpolyols are known to theskilled worker.

Additionally of suitability as a constituent of the binder component ofthe invention are polycarboxylic acids and their anhydrides such asphthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalicanhydride, hexachloroendomethylenetetrahydrophthalic anhydride,pyromellitic anhydride, benzophenone-3,3′,4,4′-tetracarboxylicdianhydride, the acids of the aforementioned anhydrides, and alsoisophthalic acid or terephthalic acid.

Likewise suitable as a constituent of the binder component of theinvention are catalytic hardeners, examples being amidines such asdicyandiamide.

A binder component of the invention further comprises at least onecompound having chelating properties.

By “chelating properties” are meant, in the context of the present text,the capacity of a compound to chelate one or more metal ions or metalatoms and so to be able to form chelates.

Compounds having chelating properties that are suitable in the contextof the present invention are compounds in which metals, groups withsingle electron pairs or with electron vacancies and hydrogen areinvolved in forming a ring. They are compounds which occupy more thanone coordination site on a metal atom, in other words are “polydentate”(the expression “multidentate” is also in use for “polydentate”). Inthis case, therefore, normally stretched compounds are formed into ringsas a result of the formation of a complex by way of a metal atom ormetal ion. The number of bound ligands depends on the coordinationnumber of the central metal. A prerequisite for the formation of achelate is that the compound that reacts with the metal contains two ormore groups of atoms which act as electron donors.

A further possible kind of chelate formation is ring closure by way ofhydrogen bonds. This case is present, for example, in α- andβ-hydroxycarbonyl compounds, i.e., hydroxycarboxylic acids,hydroxyketones, and hydroxyaldehydes, and their analogs. They alsoinclude enolizable 1,3-diketones such as acetylacetone and homologsthereof. Chelate compounds are especially stable when five- orsix-membered rings are formed.

The compounds having chelating properties that can be used in thecontext of the present invention contain in the context of the presentinvention preferably at least one functional group which allows thecompound to be incorporated into a binder. With particular preference,in the context of the present invention, a functional group of this kindis an amino group or a mercapto group. The functional group may beinvolved in the chelating properties of the compound. In the context ofthe present invention, however, it is preferred to use those compoundshaving chelating properties wherein the functional group required forincorporating the compound into the binder makes no contribution, or atleast no substantial contribution, to the chelating properties of thecompound.

A compound having chelating properties such as it may be employed inaccordance with the present invention as a constituent of the bindercomponents or binder compositions of the invention has at least twofunctional groups which make the compound capable of forming chelatecomplexes. A compound which can be used in the context of the presentinvention preferably has, for example, at least one functional group,preferably at least two functional groups, selected from the groupconsisting of SO₃H, OSO₃H, OP(O)(OH)₂, P(O)(OH)₂, P(O)HOH, COOH, OH,NH₂, NHR⁸, C(O)R⁸, CN and NO₂, R⁸ being hydrogen or a linear orbranched, saturated or unsaturated aliphatic hydrocarbon radical having1 to 10 carbon atoms.

Preferred chelating compounds have the general formula X-Z-Y, in which Xand Y each independently of one another are one of the abovementionedfunctional groups and Z is any desired aromatic or aliphatic parentstructure, Z having at least one functional group suitable forincorporating the chelating compound into a binder, and the functionalgroups X and Y being arranged on Z in such a way that they havechelating properties.

Compounds suitable in the context of the present invention as aconstituent of the binder components and binder compositions of theinvention include, for example, aliphatic compounds which not only havechelating properties but are also suitable for reaction with an epoxycompound.

Aliphatic compounds suitable for this purpose are, for example,2-amino-2-methyl-1,3-propanetriol, 3-aminomethyl-1,2-propanetriol,3-amino-1,2-propanetriol, 2-aminoalkyl-malonic acid such as2-aminomethyl-malonic acid, glutamic acid or aspartic acid.

In the context of the present invention the binder components and bindercompositions of the invention preferably include at least one aromaticamine of the general formula I, II or III, or a mixture of two or morethereof,

in which A is Y or X—Y, and Y is NH₂, NHR⁸ or SH, and X is a linear orbranched alkyl radical having 1 to 22 carbon atoms, and R¹, R², R³, R⁴,R⁵, and in formulae II and III, R⁶ and R⁷, independently of one another,are H, SO₃H, OSO₃H, OP(O)(OH)₂, P(O)(OH)₂, P(O)HOH, COOH, OH, NH₂, NHR⁸,C(O)R⁸, CN or NO₂, in which R⁸ is hydrogen or a linear or branched,saturated or unsaturated aliphatic hydrocarbon radical having 1 to 10carbon atoms, or two adjacent radicals from R¹ to R⁷ together form anaromatic or heteroaromatic ring, at least two of the radicals R¹ to R⁷not being H or part of an aromatic or heteroaromatic ring system, andthe remaining radicals being arranged such that the compound of thegeneral formula I, II or III is able to bind a divalent or polyvalentmetal ligand in chelate form.

In the binder components of the invention it is preferred to use thosecompounds in which R⁴ and R⁵ are H. It is particularly preferred if atleast one of the radicals R¹ to R³ is COOH.

Compounds suitable as chelating compounds in the context of the presentinvention contain as chelating groups preferably a combination of COOHand CHO, COOH and OH, COOH and SO₃H, COOH and COOH, SO₃H and OH, SO₃Hand CHO, OP(O)(OH)₂ and COOH, OP(O)(OH)₂ and OH, OP(O)(OH)₂ andOP(O)(OH)₂, OP(O)(OH)₂ and CHO, P(O)(OH)₂ and P(O)(OH)₂, P(O)(OH)₂ andCOOH, P(O)(OH)₂ and SO₃H, P(O)HOH and COOH, P(O)HOH and P(O)HOH, P(O)HOHand OH, CHO, P(O)HOH, and SO₃H.

In the context of the present invention it is possible for a bindercomponent of the invention or binder composition of the invention tocomprise, for example, in each case only one of the stated compoundshaving chelating properties. Likewise contemplated within the context ofthe present invention, however, is for a binder component of theinvention or binder composition of the invention to comprise a mixtureof two or more of the abovementioned chelating compounds. Thus, forexample, a binder composition of the invention which includes two bindercomponents may comprise two chelating compounds, with in each case oneof the binder components involved in the binder composition of theinvention comprising a chelating compound which is different with regardto the second binder component. It is also possible, however, inaccordance with the invention for one binder component to comprise twoor more different chelating compounds.

In one particularly preferred embodiment of the present invention abinder combination of the invention or binder of the invention comprisesaminosalicyclic acid, especially 4-amino-2-hydroxybenzoic acid or5-amino-2-hydroxybenzoic acid or a derivative thereof, or5-aminoisophthalic acid or derivative thereof, -or1-amino-2-hydroxynaphthalene-4-sulfonic acid or aminosalicylaldehyde,4-aminophthalic acid, 4-aminophthalonitrile, mercaptosalicylic acid ormercaptoisophthalic acid, or a mixture of two or more of said compounds.

A binder component of the invention may include one chelating compound,as described above, or a mixture of two or more such chelating compoundsin an amount of more than about 0.05 to about 50% by weight. Thefraction of a chelating compound or of a mixture of two or morechelating compounds in a binder component of the invention is preferablyfrom about 0.1 to about 30% by weight, in particular from about 1 toabout 25% by weight, for example, from about 2 to about 20% by weight.

Within the context of the present invention it is possible, and alsocontemplated, for a binder component of the invention to comprise thechelating compound not, or not exclusively, in free form but insteadalready wholly or partly in conjunction with a compound that is presentin the binder component. This will frequently be the case when, forexample, the chelating compound is added to a binder component whichfunctions as a resin within a binder composition. If, for example, achelating compound is added to an epoxy compound used as resin in thecontext of the present invention, then there may be reaction of theamino group or of the mercapto group of the chelating compound with theepoxy compound. If, therefore, in the context of the present text, theamount of chelating compounds in a binder component is specified, thiswill be a reference not only to the amount of free chelating compoundsin the binder component but also to the amount of bound chelatingcompounds.

The binder components of the invention are suitable for preparing bindercompositions having improved adhesion properties on a very wide varietyof substrates.

The present invention accordingly also provides a binder compositioncomprising at least one epoxy compound and at least one amino compoundhaving at least two amino groups or at least one epoxy compound and atleast one mercapto compound having at least two SH groups or at leastone epoxy compound and at least one hydroxy compound having at least twoOH groups or at least epoxy compound and at least one amino compoundhaving at least two amino groups and at least one mercapto compoundhaving at least two SH groups and at least one compound having chelatingproperties.

Likewise provided by the invention is a one-component or multicomponentbinder composition comprising at least one isocyanate having at leasttwo NCO groups and at least one compound having chelating properties.

The binder components of the invention can be prepared simply by mixingthe compounds involved in the respective binder components.

The present invention hence also provides a process for preparing abinder component of the invention, wherein at least one epoxy compoundor at least one amino compound having at least two amino groups or atleast one hydroxy compound having at least two OH groups or at least onemercapto compound having at least two SH groups or at least oneisocyanate having at least two NCO groups or a mixture of two or more ofsaid compounds is mixed with at least one compound having chelatingproperties.

The mixing in the context of the present invention can essentially takeplace at any desired temperatures at which the individual components aremiscible. Suitable temperatures are from about 10 to about 50° C., forexample. Within the context of the process of the invention, however, itis also possible and contemplated for the preparation of a bindercomponent of the invention to be conducted at an elevated temperature.This is especially advantageous in those cases where the compound havingchelating properties and the other compounds present in the bindercomponent are immiscible or only poorly miscible. In such cases, mixingat elevated temperature, for example, may bring about a chemicalreaction between the compound having chelating properties and the resincomponent, so that the compound having chelating properties or a mixtureof two or more such compounds is attached covalently to the resin togive a homogeneous mixture.

In a further preferred embodiment a binder composition of the inventioncomprises, for example, the following components:

-   -   20-90% by weight of an epoxy compound    -   3-79.9% by weight of a polymercaptan or polyamine hardener    -   0-50% by weight of fillers    -   0-35% by weight of impact modifiers    -   0-15% by weight of auxiliaries    -   0.5-50% by weight of a chelating compound or    -   35-90% by weight of an epoxy compound    -   2-10% by weight of a catalytic hardener such as dicyandiamide    -   3-40% by weight of fillers    -   0-35% by weight of impact modifiers    -   0-15% by weight of auxiliaries    -   1-12% by weight of a chelating compound or    -   40-80% by weight of an epoxy compound    -   10-60% by weight of a polymercaptan or polyamine hardener    -   0-5% by weight of auxiliaries    -   2-15% by weight of a chelating compound, in particular    -   50-80% by weight of a diglycidyl ether    -   10-49% by weight of a polyetheramine which carries at least two        amino groups, in particular a Jeffamin, or of a polyaminoamide        hardener, and    -   2-12% by weight of a chelating compound or    -   25-60% by weight of an epoxy compound    -   15-40% by weight of a polyamine or polymercaptan    -   10-40% by weight of fillers    -   0-20% by weight of impact modifiers    -   0-15% by weight of auxiliaries    -   1-12% by weight of a chelating compound

The binder components and binder compositions of the invention aresuitable for preparing surface coating compositions, particularly forpreparing adhesives.

The present invention accordingly also provides a surface coatingcomposition at least comprising a binder component of the invention, abinder component prepared in accordance with the invention or a bindercomposition of the invention.

A corresponding surface coating composition of the invention may becomposed exclusively, for example, of a binder composition of theinvention. It is, however, also contemplated in accordance with theinvention for a surface coating composition to comprise one or morefurther auxiliaries and additives as well as a binder composition of theinvention.

Examples of suitable auxiliaries and additives include stabilizers,defoamers, antioxidants, photostabilizers, pigment dispersants, fillers,plasticizers, tackifiers, dyes, including indicator dyes, microbicides,impact modifiers, and the like.

Examples of suitable plasticizers include esters such as abietic esters,adipic esters, azelaic esters, benzoic esters, butyric esters, aceticesters, esters of higher fatty acids having about 8 to about 44 carbonatoms, esters of OH-carrying or epoxidized fatty acids, fatty acidesters and fats, glycolic esters, phosphoric esters, phthalic esters,linear or branched alcohols containing 1 to 12 carbon atoms, propionicesters, sebacic esters, sulfonic esters, thiobutyric esters, trimelliticesters, citric esters, and nitrocellulose-based and polyvinylacetate-based esters, and also mixtures of two or more thereof.Particularly suitable esters are the asymmetric esters or difunctionalaliphatic dicarboxylic acids, an example being the esterificationproduct of monooctyl adipate with 2-ethylhexanol (Edenol DOA, Henkel,Dusseldorf, Germany).

Likewise suitable as plasticizers are the single or mixed ethers ofmonofunctional, linear or branched C₄₋₁₆ alcohols or mixtures of two ormore different ethers of such alcohols, examples being dioctyl ethers(available as Cetiol OE, Henkel, Dusseldorf).

In another embodiment endgroup-capped polyethylene glycols can be usedas plasticizers. For example, polyethylene or polypropylene glycoldi-C₁₋₄ alkyl ethers, especially the dimethyl or diethyl ethers ofdiethylene glycol or dipropylene glycol, and also mixtures of two ormore thereof.

Likewise suitable as plasticizers in the context of the presentinvention are diurethanes. Diurethanes can be prepared, for example, byreacting diols having OH end groups with monofunctional isocyanates, byselecting the stoichiometry such that essentially all of the free OHgroups are consumed by reaction. Any excess isocyanate can be removedsubsequently by means, for example, of distillation from the reactionmixture. Another method of preparing diurethanes consists in thereaction of monofunctional alcohols with diisocyanates, with all of theNCO groups, as far as3possible, being consumed by reaction.

For the preparation of diurethanes based on diols it is possible to usediols having 2 to about 22 carbon atoms, examples being ethylene glycol,propylene glycol, 1,2-propanediol, dibutanediol, hexanediol, octanediolor technical-grade mixtures of hydroxy fatty alcohols with about 14carbon atoms, especially hydroxystearyl alcohol. Preference is given tolinear diol mixtures, particularly those containing polypropylene glycolhaving an average molecular weight (Mn) of from about 1 000 to about 6000 in amounts of more than about 50% by weight, in particular more thanabout 70% by weight. Very particular preference is given to diurethanesbased exclusively on propylene glycol, having identical or differentaverage molecular weights of from about 1 000 to about 4 000. The freeOH groups of the diol mixtures are essentially all consumed by reactionwith aromatic or aliphatic monoisocyanates or mixtures thereof.Preferred monoisocyanates are phenol isocyanate or tolylene isocyanateor mixtures thereof.

For preparing diurethanes based on diisocyanates, aromatic or aliphaticdiisocyanates or mixtures thereof are used. Suitable aromatic oraliphatic diisocyanates are, for example, the isocyanates as indicatedabove as being suitable for preparing the polyurethane of the invention,preferably tolylene diisocyanate (TDI). The free NCO groups of thediisocyanates are essentially completely reacted with monofunctionalalcohols, preferably linear monofunctional alcohols or mixtures of twoor more different monofunctional alcohols. Mixtures of linearmonofunctional alcohols are particularly suitable. Suitable monoalcoholsare, for example, monoalcohols having 1 to about 24 carbon atoms,examples being methanol, ethanol, the positional isomers of propanol,butanol, pentanol, hexanol, heptanol, octanol, decanol or dodecanol,especially the respective 1-hydroxy compounds, and also mixtures of twoor more thereof. Likewise suitable are what are called “technical-grademixtures” of alcohols and endgroup-capped polyalkylene glycol ethers.Particularly suitable are alcohol mixtures containing polypropyleneglycol monoalkyl ethers having an average molecular weight (Me) of fromabout 200 to about 2 000 in an amount of more than about 50% by weight,preferably more than about 70% by weight, based on the alcohol mixture.Particular preference is given to diurethanes based on diisocyanateswhose free NCO groups have been fully reacted by means of polypropyleneglycol monoalkyl ether having an average molecular weight of from about500 to about 2 000.

A surface coating composition of the invention may further contain up toabout 7% by weight, in particular up to about 5% by weight, ofantioxidants.

A surface coating composition of the invention may further contain up toabout 5% by weight of catalysts for controlling the cure rate. This isespecially advantageous when the surface coating compositions areintended to cure at low temperatures, at from about 10 to about 30° C.for example, and comprise as binder a compound having relativelyunreactive functional groups, OH groups for example.

Suitable catalysts are, for example, organometallic compounds such asiron compounds or tin compounds, especially the 1,3-dicarbonyl compoundsof iron or of divalent or tetravalent tin, particularly theSn(II)carboxylates or the dialkyl-Sn(IV)dicarboxylates or thecorresponding dialkoxylates, examples being dibutyltin dilaurate,dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate,tin(II)octoate, tin(II)phenolate or the acetylacetonates of divalent ortetravalent tin. Likewise suitable are tertiary amines such as2,4,6-tris(dimethylaminoethyl)phenol, imidazoles such as1-methylimidazole, 2-ethyl-4-methylimidazole, or Mannich bases and alsosalts thereof or quaternary ammonium compounds such asbenzyldimethylamine, 2,4,6-tris(dimethylaminoethyl)-phenol,4-aminopyridine, tripentylammonium phenolate or tetramethylammoniumchloride, or substituted ureas such asN-phenyl-N′,N′-dimethylurea(fenuron),N-(4-chlorophenyl)-N′,N′-dimethylurea orN-(3-chloro-4-methylphenyl)-N′,N′-dimethylurea(chlortoluron). Theselection of further suitable catalysts, which is otherwise guided inparticular by the type of binder composition—for example, whether thatcomposition is a polyester composition or a polyurethane composition—isreadily possible for the skilled worker on the basis of the presentinvention.

A surface coating composition of the invention may contain up to about20% by weight of customary tackifiers. Examples of suitable tackifiersinclude resins, terpene oligomers, coumarone/indene resins, aliphatic,petrochemical resins, and modified phenolic resins.

A surface coating composition of the invention may contain up to about40% by weight, for example, up to about 20% by weight, of fillers.Examples of suitable fillers include inorganic compounds such as bariumsulfate, chalk, lime flour, precipitated silica, pyrogenic silica,zeolites, bentonites, ground minerals, glass beads, glass flour, glassfibers, including short-cut glass fibers, and other inorganic fillersknown to the skilled worker, and also organic fillers, especiallyshort-cut fibers or hollow plastic beads.

A surface coating composition of the invention may contain up to about2% by weight, preferably about 1% by weight, of UV stabilizers.Particularly suitable UV stabilizers are those which are called hinderedamine light stabilizers (HALS).

Particularly suitable in this respect are the products Lowilite 75 andLowilite 77 (Great Lakes, USA).

A surface coating composition of the invention may contain up to about30% by weight, for example, up to about 20% by weight, of impactmodifiers. Examples of suitable impact modifiers include 1,3-dienepolymers containing carboxyl groups, and further polar, ethylenicallyunsaturated comonomers. Examples of suitable dienes include butadiene,isoprene or chlorobutadiene, preferably butadiene. Examples of polar,ethylenically unsaturated comonomers are acrylic acid, methacrylic acid,lower alkyl esters of acrylic or methacrylic acid, their methyl or ethylesters, for example, amides of acrylic or methacrylic acid, fumaricacid, itaconic acid, maleic acid or the lower alkyl esters or monoestersthereof, or maleic or itaconic anhydride, vinyl esters such as vinylacetate, or in particular, acrylonitrile or methacrylonitrile.Particularly preferred impact modifiers are, for example,carboxyl-terminated butadiene acrylonitrile copolymers (CTBN), which aresold in liquid form under the name Hycar by the company B.F. Goodrich.These products have molecular weights of between about 2 000 and about 5000 and acrylonitrile contents of between about 10% by weight and about30% by weight. Specific examples are Hycar CBTN 1300 X8, 1300 X13 or1300 X15.

As impact modifiers it is additionally possible as well to use thecore/shell polymers known from U.S. Pat. No. 5,290,857 or from U.S. Pat.No. 5,686,509. In this case the core monomers ought to have a glasstransition temperature of −30° C. or less. These monomers may beselected, for example, from the group of the abovementioned dienemonomers or from suitable acrylate or methacrylate monomers. The corepolymer may if desired include crosslinking comonomer units in minoramount. The shell is constructed, for example, from copolymers having aglass transition temperature of at least about 60° C. The shell ispreferably constructed from lower alkyl acrylate or methacrylate monomerunits (methyl or ethyl esters, for example) and also from polar monomerssuch as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide,styrene or free-radically polymerizable, unsaturated carboxylic acids orcarboxylic anhydrides.

In one preferred embodiment the above liquid CTBN rubbers are used asimpact modifiers.

The surface coating compositions of the invention are suitable for abroad field of applications in the area of surface coatings, adhesives,and sealants. The formulations of the invention are especially suitable,for example, as a contact adhesive, one-part adhesive, two-partadhesive, assembly adhesive, sealant, especially joint sealant, and alsofor surface sealing.

They exhibit improved adhesion to substrates, particularly to metalsurfaces. Moreover, the aging stability of the substrate/polymerassembly is significantly improved, especially under moist conditions.

The invention accordingly further provides for the use of a bindercomponent of the invention or of a binder component prepared inaccordance with the invention, or of a binder composition of theinvention, in surface coating compositions.

The surface coating compositions of the invention can be in the formeither of one-part systems or of two-part systems.

The surface coating compositions of the invention are suitable, forexample, as an adhesive for plastics, metals, mirrors, glass, ceramic,mineral substrates, wood, leather, textiles, paper, paperboard, andrubber, particularly for the adhesive bonding of metals, it beingpossible for the materials in each case to be bonded to themselves orarbitrarily to one another.

The surface coating compositions of the invention are additionallysuitable, for example, as a sealant for plastics, metals, mirrors,glass, ceramic, mineral substrates, wood, leather, textiles, paper,paperboard, and rubber, it being possible for the materials in each caseto be sealed with themselves or arbitrarily from one another.

The surface coating compositions of the invention are suitable,moreover, for example, as surface coating compositions for surfaces ofplastic, metal, glass, ceramic, mineral materials, wood, leather,textiles, paper, paperboard, and rubber.

The present invention likewise provides for the use of an amino compoundhaving chelating properties as an adhesion promoter in surface coatingcompositions.

The invention is illustrated below by means of examples.

EXAMPLES Example 1

The adhesives were prepared by stirring hardener and chelating compoundat about 100° C. for about 10 minutes. After the mixture had been cooledto room temperature (RT, 20° C.) the resin was stirred in. An adhesivethus prepared was used to bond clean and degreased steel panels 25 mm inwidth with a 10 mm overlap, and the systems were cured at 120° C. for 60minutes. The bonded panels were subsequently stored for a week.Thereafter the tensile shear strength of the bond was determined.Further test specimens prepared identically were subjected to a testunder humid conditions at 70° C. and immediately following their removalwere investigated in the moist state for their tensile shear strength.

To allow the hot humid test to be carried out, the test specimens werewrapped up in a paper cloth soaked with distilled water. Thisarrangement was subsequently enclosed in aluminum foils and stored in aplastic vessel with an airtight seal at 70° C. for one week or for twoweeks. After the corresponding storage time the samples were removed,frozen at −20° C., thawed, and then immediately, at room temperature,investigated for their tensile shear strength.

In order to examine the effectiveness of the binder components of theinvention the adhesives indicated in the table below were prepared.TABLE 1 Adhesive formulations (all amounts in % by weight) Example ResinHardener Chelating compound 1 DGEBA 62.2% J D-400 37.8% — 2 DGEBA 60.2%J D-400 34.7% 4-amino-2-hydroxy- benzoic acid 5.1% 3 DGEBA 60.2% J D-40034.7% 5-amino-2-hydroxy- benzoic acid 5.1% 4 DGEBA 62.5% J D-400 33.3%5-aminoisophthalic acid 5.0% 5 DGEBA 61.7% J D-400 33.3%1-amino-2-hydroxy- naphthalene-4-sulfonic acid 5.0% 6 DGEBA 60.2% JD-400 34.7% 4-aminobenzoic acid 5.1% 7 DGEBA 60.7% J D-400 34.3%aminophenol 5.0%DGEBA = bisphenol A diglycidyl etherJ D-400 = Jeffamin D-400 (manufacturer: Huntsman Chemical Company)

Examples 1, 6, and 7 are Comparative Examples.

The tensile shear strengths found after 1 week of storage and after 1 or2 weeks in the hot humid test are reproduced in Table 2 below. TABLE 2Tensile shear strengths of the test specimens (all in MPa) Example TSS 1TSS 2 TSS 3 1 23.5 9.0 9.2 2 29.3 14.1 17.3 3 32.3 20 24.1 4 30.8 14.216.9 5 28.2 14.2 15.4 6 23.4 9.4 4.4 7 23.1 12.1 12.3TSS 1 = tensile shear strength after 1 week of storage at RTTSS 2 = tensile shear strength after 1 week of hot humid testTSS 3 = tensile shear strength after 2 weeks of hot humid test

Example 2

Reference adhesive (not inventive): the resin component of a two-partadhesive was prepared by combining 10.8 g of castor oil with 1.67 g ofBaylith L paste (zeolite-based, castor oil-containing drier,manufacturer: Bayer AG) at 20° C. Subsequently 5.19 g of UK 5400(hardener component of the solvent-free two-part adhesive Macroplast UK8202, based on isocyanates; density 1.22±0.05 g/cm³; viscosity[Brookfield RVT, 20° C.] 250±100 mPa.s; manufacturer: Henkel KgaA) wereadmixed as hardener.

Inventive adhesive: the resin component of a two-part adhesive wasprepared by combining 10.8 g of castor oil with 1.67 g of Baylith Lpaste and 0.624 g of 4-aminosalicylic acid at 20° C. Subsequently 6.28 gof UK 5400 were admixed as hardener. The additional amount of hardenerused in relation to the reference adhesive was calculated so that twoNCO groups of the hardener corresponded to one amino group of the4-aminosalicylic acid used, i.e., so that on the basis of theisocyanate-reactive amino hydrogen atoms of the 4-aminosalicylic acidused one equivalent of 4-aminosalicylic acid was compensated by twoequivalents of the isocyanate.

The adhesives were used to bond sand blasted and degreased steel panels(reference experiment 2.1 and inventive experiment 2.2) and,respectively, aluminum panels (reference experiment 2.3 and inventiveexperiment 2.4) pretreated with a chrome-free pretreatment consisting ofthe steps of the alkaline cleaning (Ridoline 1580; manufacturer HenkelKgaA), pickling (Deoxidizer 4902; Henkel KgaA), and passivating (Alodine2040; manufacturer: Henkel KgaA) over an area of 10×20 mm. The testspecimens obtained in this way were subsequently stored at 20° C. for 14days. Thereafter the tensile shear strength of the adhesive bond wasdetermined. Further test specimens produced identically were subjectedto a hot humid test at 70° C. and immediately after their removal wereinvestigated, in the moist state, for their tensile shear strength.

The hot humid test was carried out by taking the test specimens storedat 20° C. for 14 days and wrapping them in cotton wool soaked withdistilled water. This arrangement was subsequently wrapped in aluminumfoil and stored in a plastic vessel with an airtight seal at 70° C. forone week or for two weeks or for four weeks. After the correspondingstorage time the samples were removed, cooled to −30° C. for 16 hours ineach case, then brought to 20° C. and immediately investigated for theirtensile shear strength.

The tensile shear strengths determined after 2 weeks at 20° C. and after1, 2, and 4 weeks in the hot humid test are reproduced in Table 3 below.TABLE 3 Tensile shear strengths of the test specimens (all in MPa)Experiment TSS 0 TSS 1 TSS 2 TSS 4 2.1 4.3 3.2 1.9 2.1 2.2 10.2 10.9 9.78.3 2.3 3.62 3.08 3.90 3.71 2.4 5.34 8.11 6.98 5.42TSS 0 = tensile shear strength after 2 weeks of storage at 20° C.TSS 1 = tensile shear strength after 1 week of hot humid testTSS 2 = tensile shear strength after 2 weeks of hot humid testTSS 4 = tensile shear strength after 4 weeks of hot humid test

Example 3

Reference adhesive (not inventive): 20 g of UK 8202 (resin component ofthe solvent-free two-part adhesive Macroplast UK 8202, based onhydroxyl-containing organic compounds; density 1.45±0.05 g/cm³;viscosity [Brookfield RVT, 20° C.] 27 000±4 000 mPa.s; manufacturer:Henkel KgaA) and 5.0 g of UK 5400 were combined at 20° C.

Inventive adhesive: 20 g of UK 8202, 1.0 g of 4-aminosalicylic acid and6.74 g of UK 5400 were combined at 20° C. The additional amount ofhardener used as compared with the reference adhesive was againcalculated so that on the basis of the isocyanate-reactive aminohydrogen atoms of the 4-aminosalicylic acid used one equivalent of4-aminosalicylic acid was compensated by two equivalents of theisocyanate.

The adhesives were used to bond aluminum panels pretreated as in Example2 (reference experiment 3.1 and inventive experiment 3.2) and aluminumpanels merely cleaned with acetone but otherwise untreated (referenceexperiment 3.3 and inventive experiment 3.4) over an area of 10×20 mm.The test specimens obtained in this way were subjected to a procedureidentical to that of Example 2.

The tensile shear strengths determined as in Example 2 after 2 weeks at20° C. and after 1, 2, and 4 weeks in the hot humid test are reproducedin Table 4 below. TABLE 4 Tensile shear strengths of the test specimens(all in MPa) Experiment TSS 0 TSS 1 TSS 2 TSS 4 3.1 13.0 1.34 0.54 0.813.2 14.4 15.1 14.0 13.4 3.3 10.2 2.21 3.48 1.20 3.4 14.6 10.5 5.58 8.25TSS 0 = tensile shear strength after 2 weeks of storage at 20° C.TSS 1 = tensile shear strength after 1 week of hot humid testTSS 2 = tensile shear strength after 2 weeks of hot humid testTSS 4 = tensile shear strength after 4 weeks of hot humid test

1. A binder component comprising at least one epoxy compound or at leastone amino compound having at least two amino groups or at least onehydroxy compound having at least two OH groups or at least one mercaptocompound having at least two SH groups or at least one isocyanate havingat least two NCO groups and at least one compound having chelatingproperties.
 2. The binder component of claim 1, characterized in thatthe compound having chelating properties contains an amino group or amercapto group.
 3. The binder component of claim 1 or 2, characterizedin that it comprises an aromatic amine of the general formula I, II orIII

in which A is Y or X—Y, and Y is NH₂, NHR⁸ or SH, and X is a linear orbranched alkyl radical having 1 to 22 carbon atoms, and R¹, R², R³, R⁴,R⁵, and in formulae II and III, R⁶ and R⁷, independently of one another,are H, SO₃H, OSO₃H, OP(O)(OH)₂, P(O)(OH)₂, P(O)HOH, COOH, OH, NH₂, NHR⁸,C(O)R⁸, CN or NO₂, in which R⁸ is hydrogen or a linear or branched,saturated or unsaturated aliphatic hydrocarbon radical having 1 to 10carbon atoms, or two adjacent radicals from R¹ to R⁷ together form anaromatic or heteroaromatic ring, at least two of the radicals R¹ to R⁷not being H or part of an aromatic or heteroaromatic ring system, andthe remaining radicals being arranged such that the compound of thegeneral formula I, II or III is able to bind a divalent or polyvalentmetal ligand in chelate form.
 4. The binder component of claim 3,characterized in that it comprises a compound of the general formula I.5. The binder component of claim 3 or 4, characterized in that at leastone of the radicals R¹ to R⁷ is COOH.
 6. The binder component of one ofclaims 1 to 5, characterized in that it comprises as at least onecompound having chelating properties aminosalicylic acid or a derivativethereof or aminoisophthalic acid or a derivative thereof or a mixture oftwo or more of said compounds.
 7. A process for preparing a bindercomponent in accordance with one of claims 1 to 6, wherein at least oneepoxy compound or at least one amino compound having at least two aminogroups or at least one hydroxy compound having at least two OH groups orat least one mercapto compound having at least two SH groups or at leastone isocyanate having at least two NCO groups or a mixture of two ormore of said compounds is mixed with at least one compound havingchelating properties.
 8. A binder composition comprising at least oneepoxy compound and least one amino compound having at least two aminogroups or at least one hydroxy compound having at least two OH groups orat least one mercapto compound having at least two SH groups or at leastone isocyanate having at least two NCO groups or a mixture of two ormore thereof and at least one compound having chelating properties.
 9. Asurface coating composition, at least comprising a binder component inaccordance with one of claims 1 to 6 or a binder component preparedaccording to claim 7 or a binder composition according to claim
 8. 10.The surface coating composition of claim 9, characterized in that it isan adhesive.
 11. The use of a binder component in accordance with one ofclaims 1 to 6 or of a binder component prepared according to claim 7 orof a binder composition according to claim 8 in surface coatingcompositions.
 12. The use of an amino compound having chelatingproperties as an adhesion promoter in surface coating compositions.